Humble Defector

{T}: Draw two cards. Target opponent gains control of Humble Defector. Activate only during your turn.

Return the Favor

Spree (Choose one or more additional costs.)
+ {1} — Copy target instant spell, sorcery spell, activated ability, or triggered ability. You may choose new targets for the copy.
+ {1} — Change the target of target spell or ability with a single target.

Fiery Gambit

Flip a coin until you lose a flip or choose to stop flipping. If you lose a flip, Fiery Gambit has no effect. If you win one or more flips, Fiery Gambit deals 3 damage to target creature. If you win two or more flips, Fiery Gambit deals 6 damage to each opponent. If you win three or more flips, draw nine cards and untap all lands you control.

Brand

Gain control of all permanents you own. (This effect lasts indefinitely.)
Cycling {2} ({2}, Discard this card: Draw a card.)

Prisoner's Dilemma

Each opponent secretly chooses silence or snitch, then the choices are revealed. If each opponent chose silence, Prisoner's Dilemma deals 4 damage to each of them. If each opponent chose snitch, Prisoner's Dilemma deals 8 damage to each of them. Otherwise, Prisoner's Dilemma deals 12 damage to each opponent who chose silence.
Flashback {5}{R}{R}

Game of Chaos

Flip a coin. If you win the flip, you gain 1 life and target opponent loses 1 life, and you decide whether to flip again. If you lose the flip, you lose 1 life and that opponent gains 1 life, and that player decides whether to flip again. Double the life stakes with each flip.

Dictate of Kruphix

Flash
At the beginning of each player's draw step, that player draws an additional card.

Chaos Mutation

Exile any number of target creatures controlled by different players. For each creature exiled this way, its controller reveals cards from the top of their library until they reveal a creature card, puts that card onto the battlefield, then puts the rest on the bottom of their library in a random order.

Braids, Conjurer Adept

At the beginning of each player's upkeep, that player may put an artifact, creature, or land card from their hand onto the battlefield.

Plargg and Nassari

At the beginning of your upkeep, each player exiles cards from the top of their library until they exile a nonland card. An opponent chooses a nonland card exiled this way. You may cast up to two spells from among the other cards exiled this way without paying their mana costs.

Mizzix, Replica Rider

Flying
Whenever you cast a spell from anywhere other than your hand, you may pay {1}{U/R}. If you do, copy that spell and you may choose new targets for the copy. If the copy is a permanent spell, it gains haste and "At the beginning of your end step, sacrifice this permanent." (A copy of a permanent spell becomes a token.)

Sudden Substitution

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Exchange control of target noncreature spell and target creature. Then the spell's controller may choose new targets for it.

Minds Aglow

Join forces — Starting with you, each player may pay any amount of mana. Each player draws X cards, where X is the total amount of mana paid this way.

Possibility Storm

Whenever a player casts a spell from their hand, that player exiles it, then exiles cards from the top of their library until they exile a card that shares a card type with it. That player may cast that card without paying its mana cost. Then they put all cards exiled with Possibility Storm on the bottom of their library in a random order.

Wild-Magic Sorcerer

The first spell you cast from exile each turn has cascade. (When you cast your first spell from exile, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Disrupt Decorum

Goad all creatures you don't control. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)

Wild Evocation

At the beginning of each player's upkeep, that player reveals a card at random from their hand. If it's a land card, the player puts it onto the battlefield. Otherwise, the player casts it without paying its mana cost if able.

Words of Wisdom

You draw two cards, then each other player draws a card.

Treasure Nabber

Whenever an opponent taps an artifact for mana, gain control of that artifact until the end of your next turn.

Magus of the Wheel

{1}{R}, {T}, Sacrifice Magus of the Wheel: Each player discards their hand, then draws seven cards.

Font of Mythos

At the beginning of each player's draw step, that player draws two additional cards.

Chaos Wand

{4}, {T}: Target opponent exiles cards from the top of their library until they exile an instant or sorcery card. You may cast that card without paying its mana cost. Then put the exiled cards that weren't cast this way on the bottom of that library in a random order.

Temple Bell

Warp World

Each player shuffles all permanents they own into their library, then reveals that many cards from the top of their library. Each player puts all artifact, creature, and land cards revealed this way onto the battlefield, then does the same for enchantment cards, then puts all cards revealed this way that weren't put onto the battlefield on the bottom of their library.

Prosperity

Wildfire Devils

When Wildfire Devils enters the battlefield and at the beginning of your upkeep, choose a player at random. That player exiles an instant or sorcery card from their graveyard. Copy that card. You may cast the copy without paying its mana cost.

Hive Mind

Whenever a player casts an instant or sorcery spell, each other player copies that spell. Each of those players may choose new targets for their copy.

Over the Top

Each player reveals a number of cards from the top of their library equal to the number of nonland permanents they control, puts all permanent cards they revealed this way onto the battlefield, and puts the rest into their graveyard.

Khârn the Betrayer

Berzerker — Khârn the Betrayer attacks or blocks each combat if able.
Sigil of Corruption — When you lose control of Khârn the Betrayer, draw two cards.
The Betrayer — If damage would be dealt to Khârn the Betrayer, prevent that damage and an opponent of your choice gains control of it.

Mana Clash

You and target opponent each flip a coin. Mana Clash deals 1 damage to each player whose coin comes up tails. Repeat this process until both players' coins come up heads on the same flip.

Perplexing Chimera

Whenever an opponent casts a spell, you may exchange control of Perplexing Chimera and that spell. If you do, you may choose new targets for the spell. (If the spell becomes a permanent, you control that permanent.)

Wrong Turn

Target opponent gains control of target creature. (If an attacking or blocking creature changes controllers, it's removed from combat.)

Share the Spoils

When Share the Spoils enters the battlefield or an opponent loses the game, exile the top card of each player's library.
During each player's turn, that player may play a land or cast a spell from among cards exiled with Share the Spoils, and they may spend mana as though it were mana of any color to cast that spell. When they do, exile the top card of their library.

Tibalt's Trickery

Counter target spell. Choose 1, 2, or 3 at random. Its controller mills that many cards, then exiles cards from the top of their library until they exile a nonland card with a different name than that spell. They may cast that card without paying its mana cost. Then they put the exiled cards on the bottom of their library in a random order.

Winds of Change

Each player shuffles the cards from their hand into their library, then draws that many cards.

Wild Magic Surge

Destroy target permanent an opponent controls. Its controller reveals cards from the top of their library until they reveal a permanent card that shares a card type with that permanent. They put that card onto the battlefield and the rest on the bottom of their library in a random order.

Burning Inquiry

Each player draws three cards, then discards three cards at random.

Vision Skeins

Role Reversal

Exchange control of two target permanents that share a permanent type.

Whims of the Fates

Starting with you, each player separates all permanents they control into three piles. Then each player chooses one of their piles at random and sacrifices those permanents. (Piles can be empty.)

Scrambleverse

For each nonland permanent, choose a player at random. Then each player gains control of each permanent for which they were chosen. Untap those permanents.

Jace's Archivist

{U}, {T}: Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

Zoyowa's Justice

The owner of target artifact or creature with mana value 1 or greater shuffles it into their library. Then that player discovers X, where X is its mana value. (They exile cards from the top of their library until they exile a nonland card with that mana value or less. They cast it without paying its mana cost or put it into their hand. They put the rest on the bottom in a random order.)

Folio of Fancies

Players have no maximum hand size.
{X}{X}, {T}: Each player draws X cards.
{2}{U}, {T}: Each opponent mills cards equal to the number of cards in their hand.

Eye of the Storm

Whenever a player casts an instant or sorcery card, exile it. Then that player copies each instant or sorcery card exiled with Eye of the Storm. For each copy, the player may cast the copy without paying its mana cost.

Memory Vessel

{T}, Exile Memory Vessel: Each player exiles the top seven cards of their library. Until your next turn, players may play cards they exiled this way, and they can't play cards from their hand. Activate only as a sorcery.

Seething Song

Well of Ideas

When Well of Ideas enters the battlefield, draw two cards.
At the beginning of each other player's draw step, that player draws an additional card.
At the beginning of your draw step, draw two additional cards.

Guff Rewrites History

For each player, choose target nonenchantment, nonland permanent that player controls. Those permanents' owners shuffle them into their libraries. Each player who controlled one of those permanents exiles cards from the top of their library until they exile a nonland card, then puts the rest on the bottom of their library in a random order. Each player may cast the nonland card they exiled without paying its mana cost.

Chaotic Transformation

Exile up to one target artifact, up to one target creature, up to one target enchantment, up to one target planeswalker, and/or up to one target land. For each permanent exiled this way, its controller reveals cards from the top of their library until they reveal a card that shares a card type with it, puts that card onto the battlefield, then shuffles.

Lore Broker

{T}: Each player draws a card, then discards a card.

Etali, Primal Storm

Whenever Etali, Primal Storm attacks, exile the top card of each player's library, then you may cast any number of spells from among those cards without paying their mana costs.

Thieves' Auction

Exile all nontoken permanents. Starting with you, each player chooses one of the exiled cards and puts it onto the battlefield tapped under their control. Repeat this process until all cards exiled this way have been chosen.

Grip of Chaos

Whenever a spell or ability is put onto the stack, if it has a single target, reselect its target at random. (Select from among all legal targets.)

Ensnared by the Mara

Each opponent faces a villainous choice — They exile cards from the top of their library until they exile a nonland card, then you may cast that card without paying its mana cost, or that player exiles the top four cards of their library and Ensnared by the Mara deals damage equal to the total mana value of those exiled cards to that player.